The iambic trimeter derives its name from its essential shape, which is three metrical units (hence trimeter) which are each basically iambic in form. The iambic metron has the following shape (where the x is an anceps, the - is a longum, and the u is a brevis):
Hence, reversing the current running though a wire will have the affect of reversing the direction of the magnetic force at a point some distance away from the wire. The affect that this has on the overall magnetic field depends on the shape of the wire.
1 This force depends on the magnetic field, the charge and the speed. 2  The direction of this force is perpendicular to both the magnetic field and the velocity vector of the electric charge. 3  If you have an electric field in some region, that will cause a change in electric potential between two points.f you donât know the direction of the magnetic field you are trying to measure, this method wonât work. Also, if the magnetic field is very small or very large in comparison to the Earthâs horizontal component you wonât get a very accurate result.